1. Field of the Invention
The present invention relates to a novel water-in-oil (i.e., "W/O") emulsion type cosmetic composition. More specifically, it relates to a W/O emulsion type cosmetic composition having an excellent emulsification stability and excellent dispersion stability of an iron oxide pigment at a wide temperature range.
2. Description of the Related Art
In the production of W/O emulsion type cosmetics, lipophilic emulsifiers having a relatively low hydrophilic-lipophilic balance (i.e., "HLB") such as sorbitan fatty acid partial esters, polyoxyethylene (i.e., "POE") sorbitan fatty acid partial esters, glycerol fatty acid partial esters, diglycerol fatty acid partial esters, POE sorbitol fatty acid partial esters, POE alkyl ethers, and castor oil POE addition products are generally used as an emulsifier. These W/O emulsion type compositions have a relatively good stability at an ambient temperature when nonpolar oil such as paraffin oil is contained. However, in the case of nonpolar oil, the oil phase is easily separated at an elevated temperature. Furthermore, when polar oils such as triglycerides, which are selium analogues components, and waxes are contained, the W/O emulsion type compositions are inverted to an oil-in-water (i.e., O/W) emulsion or water separation from the emulsion occurs even at room temperature. Thus, the formation of stable W/O emulsion type compositions is difficult in the art. Especially when iron oxides conventionally used in the make-up type cosmetics are intended to be formulated into the above-mentioned W/O emulsion type cosmetic compositions, it is difficult to ensure the dispersion stability of the iron oxides, in addition to the above-mentioned emulsification stability. Iron oxides pigments are said to be substantially essential in make-up cosmetic compositions. Furthermore, W/O emulsion type cosmetic compositions containing an iron oxide does not flow during, for example, perspiration and, therefore, the make-up stays long. Consequently, the preparation of stable W/O emulsion type cosmetic compositions containing an iron oxide pigment is strongly desired in the art. Various attempts have been made to improve the stability of W/O emulsion type cosmetic compositions containing an iron oxide. For example, the use of various coemulsifiers such as polyols, amino acids and the salts thereof, pyrrolidone carboxylic acid salts, and metallic soaps are proposed in, for example, Japanese Examined Patent Publication No. 48-15798 and Japanese Unexamined Patent Publication No. 55-31037. However, satisfactory W/O emulsion type cosmetic compositions containing an iron oxide have not been developed yet.